Improvement in air-pumps



R. H. HOLBROOK.

AIR-PUMP.

, Patented June zo, '1976.

N. PETERS, PHoTO-LITHOGRAPHER, WASNINGYON. n C.

man SfrArns REGINALD H. HOLBROOK, OF LEBANON, OHIO.

IMPRovEMl-:NT IN AIR-PUMPS.

Specification forming part of Letters Patent No. 178,851, dated June 20, 12576; applicationlled March 15, 1876.

its stroke at the end where the valves are located there shall be no space left for the retention of any air between the .piston and the valve or end of the cylinder, all as hereinaf- `ter more fully described.

Figure lis a side elevation, shown partly in section; and Fig. 2 is a side view of a portion of the pump with the air vessels or receivers attached.

In air-pum ps as ordinarily constructed there is a space left between the piston and the inlet-valve or between the piston and the end of the cylinder or barrel, in which, at each stroke of the piston, more or less air remains, thereby preventing, to a greater 0r less extent, the perfect operation of the pump.

The object of the rst part of my invention is to overcome this objection or defect, which I -accomplish by constructing the parts as shown in Fig. 1.

In the drawings, A represents the cylinder or barrel, and B the piston of the pump. At the bottom is a tubular neck, I, which has a screw-thread for attaching the air vessel or receiver R, (shown in partial elevation in Fig. 2,) the receiver R being provided with a tube, ".ll, having a corresponding screw and a stopcock, L. From the tubular neck I a series of :small holes, r, extend up through the bottom .to the interior ot' the cylinder, as shown in lFig. 1, and in a shallow circular recess made :in the upper surface of the bottom piece is secured the valve a, which is held in place by a central screw, e, said valve being made of oiled :silk or other liexible material, and of such a :size as to just fill the recess when down.

The piston-head may be made in any suitaible manner, it being represented, in this case, :as composed of two parts, C and D, united by :screw-threads, and clasping the packing l beltween them, the latter being turned up around the exterior. It is, however, obvious that the lhead may be made solid, and the packing apbarrel as possible,

plied in any other known manner, if preferred, this forming no part of the invention.

rEhe under surface ot face of the piston-head is so formed as to tit evenly upon the upper surface of the bottom piece, as shown in Fig. 1, s0 that when'the piston is shoved down its face will come in contact with that of the bottom ofthe cylinder, thus leaving no space between them or betweenthe piston and the inletvalve a, thereby'practically excluding all air from between them. A smalll recess, e, is made in the center ot' the faceof the piston,

to t closely around the head of the screw o,

which holds the valve n in place to permit the piston-head to tit down close upon the bottom piece, thus rendering the exclusion of the air from between theml still more complete. If, however, a check -valve were substituted for this flap-valve n, and its head made to just lill the recess, and thus dispense with the screw o, the recess c in the face ot' the piston might be omitted, the prime object being to v have the face of the piston so fit the face ot' the bottom as, to leave no space for the retention of any appreciable amount of air when the piston is forced entirely down.

From one side of the bottom piece E there protrudes another tube, I', having a screwthread, which corresponds in size with the projection or tube I ,at the bottom, and within this projection I is secured an outwardlyopening valve, n, there being a small opening, t, leading therefrom into the cylinder, as shown inFig. l, through which the air escapes at each downstroke oi' the piston, the valve 'u being locatedas near the inside ofthe so as to leave the smallest amount ot' space possible for the retention of air in the passage t, which latter will ordinarily be filled at the end of the stroke by the oil around the piston.

It' it be desired to compress air into a receiver, R, the latter will be attached to the tube I', as shown in dotted lines in Fig. 2, and the pump be operated in the usual manner. If, on the other hand, it be desired to exhaust the air from a receiver, the latter will be attached to the bottom tube I, while, if itv be desired to exhaust the air from one'kreceiver v and compress it in another at the same operation, then a receiver is to be attached to both the tubes I and I', in which case, 'by operating the pump, the air will be exhausted from the receiver at the bottom and compressed or forced into the receiver at the side.

It will thus beiseen that no change of the valves and no stop-cocks or other changeable or movable fixtures are used in the pump, either to exhaust orcompress the air, or to both exhaust and compress it simultaneously, it only being necessary toconnect the receivers according as it is desired to accomplish either of these results.

By these means the construction of the pump is rendered exceedingly simple and efficient, and, consequently, will remain in working order for a much greater length of time than when provided with changeable valves, stopcocks, and other appliances ordinarily used in the class of air-pumps intended for philosophical experiments.

VIt is, of course, obvious that, if desired, there may be connected t0 the neck or projec tion I a tube so curved as to project above the bottom piece. thus enabling the receiver to be y connected thereto at a point above a base, to which the pump might be secured, if thought necessary.

In Fig. l there is shown a small hole, c, near to top of the barrel A, for entrance and' exit of air above the piston; but this, if preferred, may be made in the cap F, or there may be space sucient left around the piston-stem B to answer this purpose. i i

Having thus described my invention, what I claim is An air-pump havin g its inlet-Valve n` located upon the inside of the cylinder bottom, with a solidffaced piston of a conguration to fit` closely upon the bottom of the cylinder and the valve therein, for the purposeof excluding all air from under the piston at the end of its stroke, as set forth. l

` BEGIN ALD H. HOLBROOK.` Witnesses: y

MARION D. EGBERT, J osIAH MoRnoW. 

